Time to Call in CAT?

[dtfeld]

My port engine is noticeably louder and has a harsher sound to it than my starboard. I think Ryan @Strecker25 may have had a similar post a year or two ago. The starboard purrs, no harshness.

Port idles differently as well. When cold, Port idles much lower than starboard. Port starts at about 685 then slowing comes up to 700. Starboard starts off at 705 and stays pretty close to that. After a couple miutes both settle in at about 710.

When put in gear Port drops to around 585 which is too low (feels like its lugging) and I have to bump the throttle. Starboard is 625-630.

Both operate great at cruise and make rated WOT...2825ish.

Do I just need to adjust the Port idle or look further?

Or is it time to reset the head and check the injectors.

 

[Strecker25]

I would do the full idle adjustment first. The idle and noise might not even be related, but I did have one engine idle down much lower in gear even though the bare idle rpm's were the same - once I followed the idle adjustment procedure (with the engine hot!) they idle identical both bare and under load

As far as the noise, my mechanic was able to quickly identify the injector causing the louder knock. We used a stethoscope with the valve cover off and when placed near the #1 injector base you could hear the knock clearly. We ended up doing all 6 injectors since you need to run the entire overhead anyway. I went reman and have had no issues.

Is the 'harsher' noise a knock from the top end or somewhere else? It's really hard to ID noises in the bilge since they reverberate differently in that hole

 

[dtfeld]

I would do the full idle adjustment first. The idle and noise might not even be related, but I did have one engine idle down much lower in gear even though the bare idle rpm's were the same - once I followed the idle adjustment procedure (with the engine hot!) they idle identical both bare and under load

As far as the noise, my mechanic was able to quickly identify the injector causing the louder knock. We used a stethoscope with the valve cover off and when placed near the #1 injector base you could hear the knock clearly. We ended up doing all 6 injectors since you need to run the entire overhead anyway. I went reman and have had no issues.

Is the 'harsher' noise a knock from the top end or somewhere else? It's really hard to ID noises in the bilge since they reverberate differently in that hole

Knock is definitely from the top end. Sounds like middle of the engine...may #4 or #5.

But then again...they have always been this way...RPMs and knock since I've owned the boat.

I'll set the idle first...been meaning to do it any way.

Still may get CAT out and take a look/listen. It's been since 2018 since they took a look back in FL. They just opened a location 10 miles from the dock, so at least travel time/cost won't be as bad as when gey were 50 miles.

 

[Strecker25]

Knock is definitely from the top end. Sounds like middle of the engine...may #4 or #5.

But then again...they have always been this way...RPMs and knock since I've owned the boat.

I'll set the idle first...been meaning to do it any way.

Still may get CAT out and take a look/listen. It's been since 2018 since they took a look back in FL. They just opened a location 10 miles from the dock, so at least travel time/cost won't be as bad as when gey were 50 miles.

Certainly couldn’t hurt to have them check it out. The unfortunate part about these MUI’s is there’s not really a cutout test. That, and the fact you have to do the entire overhead regardless of doing one injector or all of them, means if it’s one it might as well be all of them.

 

[Strecker25]

One other thing my mechanic did was closely check each injector spring with the valve cover off. He said sometimes they’ll have hairline cracks (or even break) which would of course cause lots of chatter. I’d think that’s a much more pronounced sound than diesel clatter but it’s easy to visually check

 

[dtfeld]

I think I'm going set up an appt and see what they say. Ounce of prevention worth a pound of cure...